1. Field of the Invention
This invention relates to a recording and/or reproducing apparatus for a small sized optical disk adapted for recording and/or reproducing information signals on or from the optical disk accommodated in a disk cartridge.
2. Description of the Related Art
There has hitherto been utilized, as an optical recording medium for musical sound signals, video signals or other information signals, a read-only optical disk on which desired musical sound signals, or the like are prerecorded and from which the musical sound signals are reproduced on loading the disk by the user into a reproducing apparatus.
There has also been proposed, as an optical recording medium enabling signal erasure and re-recording, a magneto-optical disk employing a magnetic thin film as a recording layer.
With the optical recording medium, such as the above mentioned optical disk or magneto-optical disk, recording and/or reproduction of information signals at an extremely high density is possible because a laser beam is utilized for recording and/or reproducing the information signals. With an optical disk devoted to reading of prerecorded information signals, such as a so-called compact disk, recording of musical sound signals continuing for about 74 minutes is possible with a disk size of 12 cm. Recording of the information signals of approximately the same volume as that for the above mentioned optical disk is possible with the above mentioned magneto-optical disk.
Meanwhile, it has been contemplated to improve further the signal recording density on the optical recording medium, such as the above mentioned optical disk or magneto-optical disk. For example, for improving recording density, there has been proposed a method of compressing information signals before recording.
If such high density recording should be achieved, the same volume of the information signals as that achieved with a conventional optical recording medium may be recorded with an optical recording medium of a smaller size than the conventional recording medium.